Hybrid vehicle and method of operation

Abstract

Some vehicle maneuvers in a hybrid electric vehicle require a high discharge current from the battery. The capacity of a battery to supply a large discharge current depends on, among other things, the recent charge and discharge history. When the demand can be predicted in advance, the vehicle is operated to aggressively charge the battery during a time period close in time to the predicted event. As a result of this aggressive charging, the battery delivers more current to satisfy the power demand without allowing the terminal voltage to decrease below a minimum level than the battery would be capable of delivering at the same state of charge following a period of rest.

Description

TECHNICAL FIELD[0001]This disclosure relates to the field of hybrid electric vehicles. More particularly, the disclosure pertains to a method of operating a hybrid electric vehicle to improve the capability of a battery to satisfy short term power demands.BACKGROUND[0002]Hybrid electric vehicles improve fuel economy by storing energy in a battery during some driving conditions and utilizing that energy to supplement the power of an internal combustion engine in other driving conditions. Furthermore, hybrid electric vehicles can use a smaller internal combustion engine than a comparably sized conventional vehicle because battery power can supplement the power from the internal combustion engine to satisfy short term power requirements such as when accelerating to enter a freeway. Using a smaller engine improves fuel economy because internal combustion engines are typically more efficient when operated at a higher percentage of their maximum power capability.[0003]However, the battery...

AI Technical Summary

Benefits of technology

The patent describes a method for operating a hybrid electric vehicle that uses a prediction of future power demands to aggressively charge the battery in anticipation of high power demand events. This helps to improve the vehicle's performance and efficiency by delivering a greater current or for a longer duration while keeping the battery voltage above the minimum. The prediction of future power demands is generated based on GPS data and a database of road segments associated with speed limits or average speeds. The method takes into account changes in the battery's state of charge and age to optimize the charging process.

Problems solved by technology

However, the battery voltage decreases when power is withdrawn.

This maximum battery power limits vehicle performance with a particular engine and limits the opportunity to use a smaller engine.

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